The EU grants ‘Long-term resident’ status (LTR). Individual EU countries can grant their own version, e.g. permanent residence in Portugal. Neither the EU LTR or the Portugal permanent residence gives you unlimited access to countries other than where you were resident when granted that status.
From the ‘Moving between EU Countries’ button at https://ec.europa.eu/immigration/general-information/already-eu_en :
Going to another EU country during my long-term stay – more than 90 days
When you stay in an EU country for a long stay, usually for more than 90 days, you will generally be issued with a long-stay visa and/or a residence permit.
If your long-stay visa or residence permit has been issued by a Schengen area country, you can travel to another Schengen area country for 90 days per 180 day period. You must:
- justify the purpose of your stay;
- have sufficient financial resources for your stay and travel back;
- not be considered a threat to public policy, public security or public health.
You can also pass through other Schengen area countries on the way to your host country.
To move from one EU country to another for more than 90 days, you will need a long-stay visa or a residence permit for that country. If you wish to work, study or join your family in the second country, you may have to fulfil more conditions.